A certain kind of microorganism, such as bacteria or fungus, adheres to a carrier surface and forms a colony thereon. When the colony contains a certain number of bacillus cells, it forms/secretes an organic substance such as polysaccharide or glycoprotein that grows into a biofilm. A biofilm is akin to a medium that allows other microorganisms to enter and form a complicated microorganism group inside. Such biofilm deposits can be found everywhere in the natural environment, in industrial areas, and in humans. Such biofilm deposits cause numerous problems, including those in industrial facilities such as the erosion of metal tubing in factory drain pipes or malfunctions during valve operations, the generation of Legionella bacteria in circulating-type bathtubs, as well as various human infections including skin diseases such as pimples or skin inflammation, eye infections such as microbial keratitis via contact lenses, intraoral diseases such as caries or periodontitis, or other diseases such as otitis media, bacterial prostatitis, or cystic fibrosis pneumonia.
Many of these infections caused by biofilms (biofilm infection), for example, periodontitis, are intractable, and one reason for the intractableness is that the microorganisms in a biofilm are covered by a film (an extracellular matrix), and will therefore not directly come into contact with immune system cells or antibacterial substances. Another reason is that bacterias in a biofilm have very slow metabolisms, which is also thought to interfere with antibiotics, which show the greatest effect in actively-dividing cells. For the reasons above, in order to completely cure biofilm infections, it is necessary to ensure both the prevention of biofilm deposits by microorganisms as well as the removal of deposited biofilms.
Biofilms are generally removed physically, for example, by scraping them off with a brush, etc. However, because biofilms generally adhere tightly to a carrier surface, this is not particularly effective, even with a great deal of effort.
In light of such existing problems, compounds that can control the deposit of biofilms have been attracting attention. For example, Patent Documents 1 and 2 disclose the invention of a compound having a certain amide structure effective in the control of biofilm deposition.    Patent Document 1: WO2004/016213    Patent Document 2: WO2002/088298